Among the important petroleum refining processes that are employed in todaay's petroleum refinery are the processes for reforming a petroleum hydrocarbon stream. Such reforming processes not only produce high-octane-number hydrocarbon blending components for gasoline, but also provide a source for relatively pure hydrogen.
There are various types of reforming processes that may be employed. These include non-regenerative processes, semi-regenerative processes, cyclic or regenerative processes, and processes using a moving-bed technique. The cyclic or regenerative processes and the processes employing moving beds furnish continuous production of hydrogen and reformate. On the other hand, semi-regenerative operation requires that the production of hydrogen and reformate be stopped while the catalyst is being regenerated. While the cyclic or regenerative process and the process that employs a moving catalyst bed require expensive regeneration, piping, and valving systems, the semi-regenerative processes eliminate the investment cost for such separate regeneration, piping, and valving systems.
Heard, in U.S. Pat. No. 2,369,734, and Haensel, in U.S. Pat. No. 2,479,110 and U.S. Pat. No. 2,641,582, indicate that the catalyst employed in reforming must be regenerated after periods of service. They do not consider cyclic or regenerative processes. Hence, semi-regenerative techniques are implied, i.e., the entire amount of catalyst is taken off stream and regenerated. They do not consider a process providing continuous hydrogen production. Kluksdahl, in U.S. Pat. No. 3,537,980, also considers semi-regenerative reforming, but does not suggest a process furnishing continuous hydrogen production.
Wolf, et al., in U.S. Pat. No. 2,773,013; Snuggs, et al., in U.S. Pat. No. 2,773,014; and McHenry, et al., in U.S. Pat. No. 3,375,190 present cyclic or regenerative reforming processes.
There has now been developed a semi-regenerative process that is a compromise between the conventional cyclic or regenerative processes and the conventional semi-regenerative processes. This new improved process uses the low-investment semi-regenerative operation, but employs a limited valving and piping system which enables the lead reactor in the system to be isolated from the remainder of the reactor system. This type of operation enables the catalyst in those reactors other than the lead reactor, i.e., the catalyst in the intermediate and the tail reactors, to be regenerated while hydrogen-containing gas and low-octane-number reformate are being produced in the lead reactor.